Catalytic preparation of bis (2-nitroxyethyl) nitramine



Patented Aug. 17, 1954 CATALYTIC PREPARATION OF BIS (2- NITROXYETHYL) NITRAMINE James Cason', Jr., Nashville, Tenn, assignor to the United States of America as represented by the Secretary of the Navy No Drawing. Application December 30, 1944, Serial No. 570,811

6 Claims. (Cl. 260467) v The present invention relates to nitramines and more particularly to a new and improved method of preparing the nitramines of secondary amines.

The nitramines comprise a group of organic compounds of considerable interest at the. present time because of the great explosive strength and brisance of several members of the class; notably cyclonite (I), homocyclonite (II), Hale- ,ite (III) and DINA (IV).

CH2-1 T--OH2 CH2--I I-CHz v N 02-1 1 N-NO:

NOz-N-CH2NNO2 H2-N- H2 l lo:

I(Gye1ouite) II(Homocyclonite) I NOzNH-CH2CH2-NH-N0z (NOz-O-CHr-CHz)2N-NO2 III (Haleite) IV (DINA) All these indicated nitramines are considerably more powerful than TNT, with ballistic strengths ranging from about 1.3 toabout 1.5 times that 'of TNT. The properties of these nitramines are more particularly described in the following U. S. patents: U. S. Patent No. 2,011,571 (Hale) and U. S. Patent No. 2,461,582 (Wright et a1.)

Because of the increasing importance of this class of compounds as a whole, new methods of preparing various types of nitramines are of particular interest, and the provision of a great- 1y improved method of preparing one particular subclass of nitramines may be said to constitute one of the objects of the present invention.

A more particular object is the provision of a preparative procedure which in certain respects may be regarded as substantial improvement in, an extension of, a method originally described by Bamberger [Ben 28, 299, 537 (1895)] for the preparation of dimethylnitramine from dimethylamine nitrate by treating the latter with a lower fatty acid anhydride (acetic anhydride) according to the scheme:

The yields obtained by Bamberger in this preparation Were not reported, but when his directiom' are repeated, yields of d-imethylnitramine varying from zero to perhaps 6% are obtained.

product is obtained or very low yields are realized and the results are not reproducible. In short the method has heretofore been an isolated reaction that is entirely impractical as a preparative procedure, even on a laboratory scale. It is therefore an object of the present invention to provide a practical, reliable and general method of converting amines to the corresponding nitramine in consistently high yields.

Still another object of the present invention is to provide a catalyst that increases the yield, improves the reliability and greatly extends the applicability of the reaction by which a secondary amine nitrate is converted to the corresponding nitramine by treatment with a dehydrating acid anhydride.

Other objects and advantages will be apparent as the invention is hereinafter more particularly described.

The foregoing objects may be accomplished in accordance with the present invention by carrying out the dehydration of the amine nitrate in the presence of a small proportion of a catalyst comprising any material capable of forming ionizable bromide ion in the reaction system.

In other words the invention is based upon the discovery that if a catalytic amount of a bromide-ion-forming material is added to the reaction mixture Wherein a secondary amine nitrate is being treated with a dehydrating acid anhydride, greatly enhanced and consistently reliable yields of the corresponding nitramine are obtained.

Actually under the reaction conditions, when the catalysts of the present invention are added to the reaction mixture, they may be essentially unchanged, or they may form free HBr, or they may in part be converted to other compounds by reaction with the reagents present in the mixture. Indeed, the fate and mechanism by which the added catalyst aiiects the reaction is not definitely known. In any event, regardless of the form or state of the catalyst, the addition of the bromide-ion-forming compounds to the amine nitrate-anhydride reaction mixture in accordance with the present invention results in a very significant improvement in yield, vastly improves the reproducibility of the results, and converts what was formerly an impractical and isolated reaction into a reliable and general preparative method for producing nitramines, especially those of the type:

Inasmuch as any material capable of liberating l-IBr constitutes the preferred catalyzing agent of the present invention, it will be apparent that a wide variety of compounds may be selected as the catalyst. Among these, the following types may be mentioned purely by way of an example: Free bromine; HBr; or metal or metalloid bromides such as zinc bromide and a wide variety of obviously equivalent compounds, all of which will hereinafter be referred to generally as bromide-ion-forming materials. The catalyst is preferably used in the proportions of about 0.00075 mole to about 0.08 mole per mole of amine or amine nitrate undergoing treatment.

In some instances it is most convenient initially to prepare and isolate the secondary amine nitrate, and then subsequently to treat the isolated nitrate salt with a lower fatty acid anhydride and a small amount of the catalyst. In other cases, it may be more, convenient to prepare the amine nitrate and then to bring the nitric acid solution of the unisolated nitrate into For dehydration, a mixture of 7.6 g. (7.1 00., 0.075 mole) of acetic anhydride, 0.32 g. (0.2 cc., 0.005 mole) of 98% nitric acid, 0.00075 mole of catalyst and 6.45 g. (0.025 mole) of bis-nitroxy- I ethylamine nitrate was stirred in a small beaker,

a thermometer being placed in the center. The reaction was allowed to heat spontaneously and cooled if necessary to keep the temperature from contact with the anhydride and the catalyst. In still other cases it may be preferable to treat the secondary amine simultaneously with a. nitrating agent such as concentrated nitric acid, a lower fatty acid anhydride and a small amount of the selected catalyst. In the latter cases in particular, it is conceivable that a part of the bromide may be converted by the nitric acid in the reaction mixture, either to free halogen or to other compounds containing bromine in a different state of oxidation than in the added bromide. Be that as it may, however, the conversion of the secondary amine nitrate to the corresponding nitramine takes place to a far greater extent and in much more reliable and reproducible manner if a bromide-ion-forming material is added to the reaction mixture, regardless of whether the amine nitrate is (1) separately prepared and isolated before being treated with anhydride in the presence of the catalyst or is (2) formed in situ by treatment with a nitrating agent in the presence of the anhydride and the added catalyst.

As above indicated the catalyzed reaction of the present invention appears to be generally adaptable to the conversion of secondary amines or secondary amine nitrates to the corresponding nitramine.

In order more clearly to disclose the nature of the present invention a specific example will now be described in particular detail. t should be clearly understood, however, that this is done solely by way of example and not for the purpose of delineating the breadth of the invention or restricting the ambit of the appended claims.

Example Bis-nitroxyethylamine nitrate was prepared from refractionated diethanolamine, M. P. 270; yield of salt 75.0%, M. P. 111.7-113.2. Material used for dehydration was crystallized from I methanol or ethanol, M. P. 119.1-120.3.

It will be apparent to those skilled in the art that many variations in proportions, conditions and reactants may be made in the foregoing example without departing from the spirit and scope of the invention. All such modifications are to be understood as included within the scope of the appended claims.

We claim:

1. In the preparation of bis(2-nitroxyethyl) nitramine, the improvement which comprises treating diethalonamine nitrate with a lower fatty acid anhydride in the presence of a small proportion of a bromide as a catalyst.

2. In the preparation of bis(2-nitroxyethyl) nitramine, the improvement which comprises treating diethanolamine with nitric acid and a lower fatty acid anhydride in the presence of a small proportion of a bromide as a catalyst.

3. In the preparation of bis(2nitroxyethyl) nitramine the improvement which comprises treating 1 mole of diethanolamine with at least 3 moles of nitric acid and at least 2 moles of acetic anhydride, in the presence of less than 0.05 mole of bromide as a catalyst.

a. The method of claim 3 wherein said catalyst comprises hydrogen bromide.

5. The method of claim 3 wherein said nitric acid comprises to nitric acid.

6. The method of claim 3 wherein said catalyst is present in the proportions of about 0.00075 mole to about 0.08 mole per mole of diethanolamine.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,560,427 Moran Nov. 3, 1925 2,481,283 Blomquist et a1 Sept. 6, 1949 

1. IN THE PREPARATION OF BIS(2-NITROXYETHYL) NITRAMINE, THE IMPROVEMENT WHICH COMPRISES TREATING DIETHALONAMINE NITRATE WITH A LOWER FATTY ACID ANHYDRIDE IN THE PRESENCE OF A SMALL PROPORTION OF A BROMIDE AS A CATALYST. 